As housing costs continue to rise throughout Greater Boston, homeowners are looking for smarter ways to maximize their property’s potential. One of the fastest-growing trends is building an Accessory Dwelling Unit (ADU)—sometimes called an in-law apartment, backyard cottage, carriage house, or granny flat.

At Velney Construction, we help homeowners design, permit, and build high-quality ADUs throughout Somerville, Massachusetts. Whether you’re planning a detached backyard cottage, converting a basement into a legal apartment, transforming a garage into living space, or adding an attached ADU to your existing home, our experienced team guides you from concept through final inspection.

Our goal is simple: make the process as smooth as possible while delivering a beautiful, energy-efficient living space that increases your property’s value and creates long-term opportunities for your family.

Unlike many general contractors, we understand the unique challenges of building in Somerville. From navigating local permitting requirements to coordinating inspections and working with experienced architects and engineers, our knowledge of the city’s construction process allows us to help clients avoid costly delays and unexpected obstacles.

If you’re searching for an ADU contractor in Somerville, MA, you’ve come to the right place.

Table of Contents

• What Is an Accessory Dwelling Unit (ADU)?
• Why ADUs Are Growing in Popularity Across Massachusetts
• Understanding Massachusetts’ New Protected ADU Law (760 CMR 71.00)
• How the New ADU Law Impacts Somerville Homeowners
• Somerville Backyard Cottage Requirements
• Types of ADUs We Build
• Benefits of Building an ADU
• Why Choose Velney Construction
• Our ADU Design-Build Process
• Frequently Asked Questions
• Schedule Your Free Consultation

What Is an Accessory Dwelling Unit (ADU)?

An Accessory Dwelling Unit (ADU) is a fully functional residential living space built on the same lot as an existing home. Although smaller than the primary residence, an ADU contains everything needed for independent living, including:

• A kitchen
• Bathroom
• Sleeping area
• Living room
• Private entrance
• Mechanical systems

ADUs can be attached to your existing home, built inside your current structure, or constructed as an entirely separate building.

Common types of ADUs include:

• Detached backyard cottages
• Garage conversions
• Basement apartments
• Above-garage apartments
• Home additions
• Attached in-law suites

As Massachusetts continues addressing its housing shortage, ADUs have become one of the most practical solutions for homeowners looking to maximize their property while creating additional housing opportunities.

For many homeowners, an ADU is no longer simply an extra building—it is a long-term investment that provides flexibility, additional income, and increased property value.

Why ADUs Are Becoming So Popular in Massachusetts

Massachusetts faces one of the country’s most competitive housing markets. Limited land, rising home prices, and increasing rental demand have encouraged lawmakers to rethink how residential properties can be used more efficiently.

Accessory Dwelling Units provide homeowners with an opportunity to add housing without dramatically changing the character of established neighborhoods.

Many homeowners choose to build an ADU because it allows them to:

• Generate rental income
• Create housing for aging parents
• Provide an independent living space for adult children
• Increase property value
• Build a guest house
• Create a home office
• Develop a private studio
• House caregivers
• Plan for retirement income
• Age in place while remaining close to family

Rather than purchasing a second property, many homeowners are discovering they can unlock the value of the property they already own.

Because ADUs generally require less land, fewer building materials, and lower maintenance costs than traditional single-family homes, they are among the most cost-effective residential investments available today.

Massachusetts’ New Protected ADU Law (760 CMR 71.00)

One of the biggest developments for homeowners interested in building an ADU is the adoption of 760 CMR 71.00, Massachusetts’ Protected Accessory Dwelling Unit regulations.

These new regulations have significantly changed how qualifying ADUs can be approved throughout the Commonwealth.

Under the new state regulations, qualifying “Protected Use ADUs” may be allowed as of right, meaning homeowners may not need to obtain discretionary local zoning approvals that were previously required.

Generally, a qualifying Protected Use ADU:

• Is located on a single-family residential lot.
• May be attached, detached, or internal.
• Cannot exceed 900 square feet, or 50% of the gross floor area of the primary dwelling, whichever is smaller, unless a municipality permits a larger size.
• Must meet applicable building and safety codes.
• Allows only one Protected Use ADU per lot.

One of the most important aspects of the law is that a qualifying ADU may still be considered a Protected Use ADU even if other aspects of the property are considered nonconforming under local zoning, provided the ADU otherwise meets the state’s definition.

This legislation represents one of the most significant housing reforms in Massachusetts in recent years and opens new opportunities for homeowners interested in adding an accessory dwelling unit.

Because these regulations are still relatively new, working with an experienced contractor who understands both state requirements and local permitting is more important than ever.

What Does This Mean for Somerville Homeowners?

Somerville has long been recognized as one of Massachusetts’ most progressive communities regarding housing and smart urban development.

However, with the introduction of the state’s Protected ADU regulations, homeowners now have an additional pathway that may allow qualifying ADUs to proceed without certain traditional zoning hurdles.

Every property is unique.

Factors such as:

• Lot size
• Existing setbacks
• Utility connections
• Fire protection requirements
• Building code compliance
• Historic district considerations
• Existing site conditions

can all influence whether a proposed ADU qualifies under state regulations or must instead follow the City’s local zoning ordinance.

At Velney Construction, we work closely with architects, engineers, surveyors, and municipal officials to evaluate each property individually. Before construction begins, we help determine which approval pathway makes the most sense for your project and coordinate with the appropriate professionals to keep the process moving efficiently.

As these regulations continue to evolve, having an experienced local contractor who understands Somerville’s permitting process and Massachusetts’ ADU legislation can make a significant difference in your project’s success.

Understanding Somerville’s Backyard Cottage Regulations

In addition to the new state regulations, Somerville’s Zoning Ordinance includes provisions for Backyard Cottages, which are detached accessory buildings that can provide independent living space on the same lot as the principal residence.

According to the City’s zoning ordinance, Backyard Cottages are intended to support uses such as:

• Small dwelling units
• Home occupations
• Children’s playhouses
• Accessory parking structures

Somerville also establishes several important design requirements, including:

• A minimum three-foot-wide paved walkway capable of accommodating emergency medical access.
• Underground utility service connections.
• Automatic sprinkler requirements for many residential Backyard Cottages unless specific site conditions qualify for an exception.

Because local ordinances and state regulations may both apply depending on your property’s characteristics, we encourage homeowners to review the City’s official zoning resources and consult with experienced professionals early in the planning process. You can review Somerville’s zoning regulations through the City’s official Municipal Code Document Viewer.

Understanding how these local requirements interact with Massachusetts’ Protected ADU regulations is one of the many ways Velney Construction helps homeowners make informed decisions before investing in design and permitting.

Types of ADUs Velney Construction Builds in Somerville, MA

Every homeowner has different goals when building an Accessory Dwelling Unit. At Velney Construction, we understand there is no one-size-fits-all solution. Our design-build approach allows us to customize every ADU around your property, your family’s needs, your budget, and the City’s permitting requirements.

Whether you want to create rental income, build housing for family members, or increase your home’s long-term value, we can help you determine the best type of ADU for your property.

Detached Backyard ADUs

Detached ADUs, commonly called Backyard Cottages, are becoming one of the most desirable ways to add living space in Somerville.

A detached ADU is a completely separate building located on the same lot as your primary residence. These structures provide the greatest amount of privacy because they function almost like a small home while remaining part of your existing property.

Detached ADUs are an excellent option for:

• Aging parents who want independence while staying close to family
• Adult children saving for their first home
• Long-term rental income
• Guest accommodations
• Live-in caregivers
• Home offices
• Private studios

Because these structures are built from the ground up, homeowners have greater flexibility in designing efficient floor plans, maximizing natural light, and incorporating high-performance building materials.

Basement ADU Conversions

Many Somerville homes have unfinished or partially finished basements with tremendous potential.

Rather than allowing this valuable square footage to go unused, a basement conversion can transform existing space into a fully functional apartment complete with:

• Kitchen
• Bathroom
• Bedroom
• Living area
• Laundry
• Separate entrance (when feasible)

Converting a basement into an ADU is often one of the most cost-effective ways to add living space because much of the building envelope is already in place.

However, basement ADUs require careful planning to address:

• Ceiling height
• Moisture management
• Structural considerations
• Egress requirements
• Fire separation
• Mechanical systems
• Energy efficiency
• Building code compliance

Our team works closely with architects and engineers to ensure every basement conversion meets applicable Massachusetts Building Code requirements while creating a comfortable place to live.

Garage Conversion ADUs

An underutilized garage can become one of the most valuable spaces on your property.

Garage conversions are growing in popularity because the existing foundation and structure often reduce overall construction costs.

A properly designed garage ADU can provide:

• Rental income
• Guest accommodations
• Housing for family members
• Home office space
• Private studio

Each garage conversion begins with a structural evaluation to determine whether the existing building can support the proposed design.

Attached ADUs

Attached ADUs are built as additions connected directly to the primary residence while maintaining a separate living space.

Many homeowners choose this option because it offers privacy while minimizing construction costs associated with a completely detached structure.

Attached ADUs are especially popular for:

• Multigenerational families
• In-law apartments
• Caregiver housing
• Aging in place

When designed correctly, attached ADUs blend seamlessly with the architecture of the existing home.

Why Homeowners Build ADUs

One of the reasons ADUs continue to grow in popularity is their flexibility.

Unlike many home improvement projects that serve only one purpose, an ADU can evolve with your family’s changing needs over time.

Today it may serve as a home office.

Five years from now, it could become an apartment for your parents.

Eventually, it could provide retirement income through long-term rental opportunities.

Few residential investments offer this level of flexibility.

Generate Additional Rental Income

For many homeowners, rental income is one of the primary motivations for building an ADU.

An accessory dwelling unit can generate monthly cash flow that helps offset:

• Mortgage payments
• Property taxes
• Insurance
• Maintenance costs
• Retirement planning

As rental demand throughout Somerville and Greater Boston continues to remain strong, many homeowners see ADUs as both a lifestyle improvement and a long-term financial investment.

Increase Your Property Value

A professionally designed and legally permitted ADU can significantly increase your property’s overall market value.

Today’s buyers are increasingly looking for homes that offer:

• Rental income potential
• Flexible living arrangements
• Multigenerational housing
• Home office space

A thoughtfully designed ADU makes your property stand out in an increasingly competitive housing market.

Age in Place

Many families want aging parents nearby without sacrificing everyone’s independence.

An ADU allows family members to remain close while maintaining their own kitchen, bathroom, and private living space.

This arrangement often provides a better quality of life than assisted living facilities while allowing families to support one another.

Give Adult Children Independence

With rising home prices across Massachusetts, many young adults are remaining at home longer while saving for their own property.

An ADU provides independence without requiring your children to move far away.

Many homeowners view this as an investment in their family’s future while maintaining flexibility for years to come.

Why Choose Velney Construction to Build Your ADU?

Choosing the right contractor may be the single most important decision you make during your ADU project.

At Velney Construction, we believe homeowners deserve more than someone who simply builds walls and installs finishes.

You deserve a construction partner who understands permitting, project management, energy-efficient construction, scheduling, budgeting, and municipal approvals.

That is exactly what we provide.

Local Experience Matters

Velney Construction is proudly based in Somerville, Massachusetts.

Unlike contractors who occasionally work in the city, our team understands the unique challenges of building here.

We regularly navigate:

• Building permits
• Utility coordination
• Inspection scheduling
• Historic considerations
• Tight urban job sites
• Limited access properties
• Local building regulations

Our familiarity with Somerville’s construction environment helps homeowners avoid unnecessary delays while keeping projects moving efficiently.

I Hold an Unrestricted Construction Supervisor License (CSL)

I hold an Unrestricted Massachusetts Construction Supervisor License (CSL).

This license allows our company to supervise and construct a wide variety of residential building projects requiring permits throughout Massachusetts.

For homeowners, this provides confidence that your contractor has demonstrated the knowledge necessary to perform complex construction projects while complying with state building codes.

Wentworth Institute of Technology Graduate

I earned my Bachelor of Science in Construction Management from Wentworth Institute of Technology.

Wentworth is nationally recognized for producing construction professionals who combine technical knowledge with practical field experience.

This educational background provides a strong foundation in:

• Construction estimating
• Project scheduling
• Building systems
• Structural coordination
• Construction management
• Cost control
• Quality assurance

That knowledge is applied to every ADU project we build.

E-Contractor Academy ADU Certification

Velney Construction has completed the 15-hour E-Contractor Academy Accessory Dwelling Unit Construction Business Training Program.

This specialized training focused specifically on the emerging Massachusetts ADU market and included instruction in:

• Green building practices
• High-performance ADU construction
• Business planning
• Financing and capital access
• Massachusetts ADU market opportunities
• Common ADU challenges
• Design-build project delivery
• ADU estimating and budgeting

Because Massachusetts’ ADU regulations continue to evolve, we believe ongoing education is essential to delivering the highest level of service to our clients.

This additional training allows us to better guide homeowners through one of the fastest-growing segments of residential construction.

Passive House Certified Builder

As building codes continue evolving toward greater energy efficiency, many homeowners are looking for builders who understand high-performance construction.

I am also a Certified Passive House Builder, providing valuable expertise in energy-efficient design principles.

While not every ADU will pursue Passive House certification, the building science behind these standards can help homeowners benefit from:

• Lower energy bills
• Better indoor air quality
• Increased comfort
• Improved insulation performance
• Reduced air leakage
• Long-term durability

Building smarter today can save homeowners thousands of dollars over the life of their ADU.

OSHA 30 Certified

Safety remains one of our highest priorities.

I earned an OSHA 30 Certification, demonstrating advanced training in construction safety and jobsite management.

I believe every worker should return home safely at the end of every workday, and maintaining a clean, organized, and well-managed project benefits both our employees and our clients.

Safe job sites lead to better quality, fewer delays, and more successful projects.

Design-Build Services from Start to Finish

Building an ADU involves much more than construction.

Our design-build approach helps streamline the process by coordinating every phase of your project, including:

• Initial feasibility consultation
• Budget development
• Site evaluation
• Architectural coordination
• Engineering
• Permit applications
• Construction
• Inspections
• Final walkthrough

Instead of managing multiple companies yourself, you’ll have one experienced team guiding your project from concept to completion.

Our ADU Construction Process

At Velney Construction, we believe that a successful ADU project begins long before construction starts. Careful planning, budgeting, design coordination, and permitting all play a critical role in delivering a successful project.

Our proven design-build process simplifies what can otherwise feel like an overwhelming experience.

Step 1: Initial Consultation

Every project starts with a conversation.

During our consultation, we take the time to understand:

• Your goals for the ADU
• Your budget
• Your property’s existing conditions
• Your timeline
• Whether the ADU will be used for family, rental income, or another purpose

We also discuss potential site challenges, zoning considerations, and the overall feasibility of your project.

Step 2: Site Evaluation

No two properties in Somerville are alike.

Our team evaluates your property to determine factors such as:

• Existing setbacks
• Available yard space
• Utility locations
• Drainage
• Topography
• Existing structures
• Tree impacts
• Fire access
• Existing utilities

This early evaluation helps identify potential issues before money is spent on construction drawings.

Step 3: Design & Architectural Coordination

Once the project is deemed feasible, we coordinate with experienced architects and engineers to begin preparing construction drawings.

During this phase, we focus on:

• Efficient floor plans
• Natural lighting
• Storage
• Accessibility
• Mechanical systems
• Structural design
• Energy efficiency
• Future maintenance

Because we are involved throughout the design process, we can often identify cost-saving opportunities before construction begins.

Step 4: Budget Development

One of the biggest concerns homeowners have is understanding the cost of building an ADU.

Rather than providing unrealistic estimates, we prepare detailed budgets based on your specific project.

Our preconstruction process allows homeowners to make informed decisions before construction begins.

Step 5: Permitting

Permitting is one of the most important stages of any construction project.

Our team coordinates permit applications and works with architects, engineers, and municipal departments to advance the approval process.

Because we regularly work in Somerville, we understand the City’s review process and can help keep projects moving efficiently.

Step 6: Construction

Once permits are approved, construction begins.

Throughout construction, we maintain regular communication with homeowners while coordinating:

• Demolition (when necessary)
• Site preparation
• Foundations
• Framing
• Roofing
• Windows
• Exterior finishes
• Plumbing
• Electrical
• HVAC
• Insulation
• Drywall
• Interior finishes
• Flooring
• Cabinets
• Painting
• Final punch list

Our goal is to deliver a finished ADU that reflects the same quality and craftsmanship we would expect in our own homes.

Step 7: Final Inspection & Project Closeout

Before we consider your project complete, we coordinate all required inspections and address any remaining punch list items.

Our goal is to ensure your new ADU is ready for occupancy and built to the highest standards of quality and safety.

Building Energy-Efficient ADUs

Energy efficiency is becoming increasingly important in Massachusetts construction.

As a Certified Passive House Builder, I understand how thoughtful design and quality construction can improve both comfort and long-term operating costs.

Many homeowners choose to incorporate energy-efficient features into their ADUs, including:

• High-performance insulation
• Air sealing
• Energy-efficient windows and doors
• Heat pump heating and cooling systems
• LED lighting
• Low-flow plumbing fixtures
• ENERGY STAR® appliances
• Balanced ventilation systems
• Sustainable building materials

Although every project has a different budget, investing in energy efficiency can reduce utility costs while improving indoor comfort for decades to come.

What Does an ADU Cost in Somerville, MA?

One of the most common questions we receive is:

“How much does it cost to build an ADU?”

The answer depends on several factors.

Every property is different, and every homeowner has unique goals.

Factors that influence cost include:

• Attached vs. detached ADU
• Existing site conditions
• Utility connections
• Foundation requirements
• Architectural complexity
• Interior finishes
• Size of the unit
• Structural modifications
• Mechanical systems
• Permit requirements
• Energy-efficiency upgrades

Rather than relying on online cost calculators, we recommend scheduling a consultation so we can provide a realistic budget tailored to your property.

Why Investing in an ADU Makes Financial Sense

Building an ADU is more than adding square footage—it’s an investment in your property’s future.

Benefits may include:

• Increased home value
• Rental income
• Greater flexibility for changing family needs
• Housing for aging parents
• Private space for adult children
• Improved resale value
• Additional equity
• Better use of underutilized land

For many homeowners, an ADU becomes one of the best long-term investments they make.

Frequently Asked Questions

Can I legally build an ADU in Somerville?

Many properties may qualify to build an ADU, but eligibility depends on your lot, existing conditions, zoning, and applicable state regulations. We can help evaluate your property and determine the best approval path.

What is a Protected Use ADU?

A Protected Use ADU is a qualifying Accessory Dwelling Unit recognized under Massachusetts regulation 760 CMR 71.00, which may allow certain ADUs to be approved as of right if they meet the state’s requirements.

What is the maximum size of an ADU?

Under the current Massachusetts regulations, qualifying Protected ADUs are generally limited to 900 square feet or 50% of the gross floor area of the principal dwelling, whichever is smaller, unless the municipality allows a larger size.

Can I build a detached backyard cottage?

Yes. Many homeowners choose detached ADUs, commonly referred to as Backyard Cottages, when their property and applicable regulations allow.

Can I rent out my ADU?

Many homeowners build ADUs specifically for long-term rental income. We recommend confirming all applicable state and local regulations before renting your unit.

How long does construction take?

Every project is unique. The overall timeline depends on design, permitting, weather, site conditions, and construction complexity.

Do I need an architect?

Most ADU projects require architectural and engineering services. We coordinate with experienced design professionals as part of our design-build process.

Does Velney Construction handle permits?

Yes. We assist clients through the permitting process and coordinate with the appropriate professionals and municipal departments throughout the project.

Why should I hire a contractor experienced in Somerville?

Every municipality has different permitting procedures, inspection requirements, and local regulations. Working with a contractor who regularly builds in Somerville can help reduce delays and improve communication throughout the project.

Can my ADU be energy efficient?

Absolutely. We encourage homeowners to consider high-performance construction methods that improve comfort, reduce operating costs, and increase long-term durability.

Why should I choose Velney Construction?

Velney Construction combines local experience, professional licensing, advanced certifications, and a commitment to quality craftsmanship.

Our qualifications include:

• Unrestricted Massachusetts Construction Supervisor License (CSL)
• Wentworth Institute of Technology Construction Management graduate
• Certified Passive House Builder
• OSHA 30 Certified
• Graduate of the E-Contractor Academy 15-hour Accessory Dwelling Unit Construction Business Training Program
• Extensive experience managing residential and commercial construction projects throughout Somerville and Greater Boston

When you choose Velney Construction, you’re partnering with a company that understands both the technical requirements of construction and the unique permitting landscape of Somerville.

Build Your ADU with Confidence

Building an Accessory Dwelling Unit is one of the smartest investments many Massachusetts homeowners can make. Whether you’re creating housing for loved ones, generating rental income, or increasing the value of your property, choosing the right contractor is essential.

At Velney Construction, we take pride in helping homeowners transform their ideas into well-designed, code-compliant, and energy-efficient living spaces. From the first consultation through the final inspection, our team is committed to professionalism, clear communication, and quality craftsmanship.

If you’re looking for an experienced ADU contractor in Somerville, MA or a trusted construction company that builds ADUs in Somerville, MA, we’d be honored to discuss your project.

Contact Velney Construction today to schedule a consultation and learn how we can help bring your ADU vision to life.

Conclusion

The future of housing in Massachusetts is evolving, and Accessory Dwelling Units are leading the way. As state regulations continue to create new opportunities for homeowners, there has never been a better time to explore whether an ADU is the right investment for your property.

At Velney Construction, we don’t just build ADUs—we help homeowners navigate every step of the journey with confidence. Our local experience, advanced certifications, and commitment to high-quality construction allow us to deliver projects that are functional, beautiful, and built to last.

Whether you’re envisioning a detached backyard cottage, an in-law suite, a garage conversion, or a basement apartment, our team has the knowledge and experience to help you maximize your property’s potential. We look forward to helping you create a space that serves your family today and adds value for years to come.